If you ever find out what it is please let me know. On mine I thought it was rust but later found out it wasn't.
I had the same problem when I first planted raspberries. My raspberries were a disaster. Lots of young shoots died with the same color leaves as yours. I had to reorder them. They did way better in summer and fall than in the spring. The second year same problem but less. This year my rasperberries are looking great. Should be harvesting soon.
The only change was spraying for insects. Insects do infect raspberries with diseases. The only reason I sprayed was when I watered them a bunch of insects where scrambling to avoid the water and watering wand as i shuffled the canes below. Insects destoyed my entire fruit tree crop last year so I am targeting them now.
Just dont give up. Some years some plants do great and other not so. You just need to bank on the good years with differnt varities. The heritage did the best (not as good but better than the others) the first 2 year. This year they have less canes that are less healthy. However, the Crimson reds which barely gave me anything the first 2 years are loaded right now. The Yellow Ann and pink champange also barely gave me fruit the first 2 years. They are also loaded.
I think they need to get used to the particular environment before they thrive. It probably helps that I cleanup all the leaves I cant get in the fall and spring. I also keep a watch for cane borers and remove that right away. At least that is what i experienced.
MOD
